Electrochromism can produce interesting phenomenon based on redox reaction that owns a reversible and persistent changing in color and optical transmittance by a small applied electric voltage pulse difference. The materials having electrochromic properties are called electrochromic materials, which can be classified into inorganic and organic materials. The inorganic materials can further include metal oxides, such as tungsten trioxide (WO3) and covalent metal complex compounds, such as Prussian blue. The organic materials can further include small molecule materials, such as viologen, and polymer materials, such as phthalocyanine. For electrochromic devices made of electrochromic materials, only a small electric voltage is required to drive color changes. Compared to other active color changing technologies, the applications of electrochromic devices are more extensive. In addition, EC device can be applied to the power saving field or electronic products, include power-saving smart windows, automotive sunroofs, anti-glare rearview mirrors, e-papers, and displays.
For instance, take power-saving smart windows by adjusting the transparency of electrochromic devices, indoor temperature and luminance can be modulated accordingly. To elaborate, in summer, by applying a voltage across electrochromic devices, the devices will be colored and their transparency will be lowered. Then the radiation heat from the sunlight can be blocked from buildings and thus reducing the loading of indoor air conditioners. In winter, the electrochromic devices can be discolored to increase the transparency. Then the sunlight can illuminate building for modulating indoor temperature as well as providing natural lighting. Hence, the efficacy of environmental protection and saving power can be achieved.
Current methods for fabricating electrochromic device adopt costly magnetic plasma sputters, leading to expensive manufacturing costs. Due to electrochromic materials are mostly target materials with high melting points, the problem of target poisoning occurs and thereby the yield is inferior, which also increase the manufacturing costs using magnetic plasma sputters. Consequently, electrochromic devices are pricy and not applicable to domestic and commercial buildings. Their prevalence in the market is still low.
Besides, the electrochromic device comprises an electrolyte layer, which is a conductive layer and for facilitating electron transport. The electrochromic devices according to the prior art adopt organic gel or liquid electrolyte. Unfortunately, while situated in areas having drastic temperature changes, the endurance as well as the leakage of organic gel or liquid electrolyte is questionable. Moreover, for the application market of miniature electrochromic products such as color-changing electronic tags or smart cards capable of displaying remaining power, current fabrication technology faces bottlenecks in development.
Given the problems encountered by the electrochromic devices according to the prior art, the present invention provides a method for fabricating electrochromic device. By the improved method for fabricating, the manufacturing costs can be lower and higher deposition rate using the vacuum cathodic arc-plasma technique. In addition, for meeting the trend of miniature electrochromic products, the electrochromic devices fabricated in the method for fabricating according to the present invention are highly durable, and hence truly exhibiting industrial practicality and applicability.